I'd vote for SPD with the spring tension turned all the way down. Or if you want to be super safe multi release cleats.
But really it's not a big deal. Everyone falls over once, but after that you'll get used to the heel kick. Don't overthink it. If you're thinking "OMG when i'm gonna fall over" the whole time when riding your bike then you'll definitely fall over. Tons of people ride clipless, it's nothing special.
You probably fell over when you were learning how to ride a bike, but I guess you don't fall over now. Same thing with clipless.
Last edited by Facanh; 08-01-18 at 05:23 AM.